There is a famous quote by the Greek philosopher Heraclitus: "The only constant in life is CHANGE." The same applies in Orthodontic treatment, and the mentioned change here is relapse. Any unfavourable change in tooth position away from the corrected malocclusion after orthodontic treatment is termed a relapse in orthodontics. Maintaining the teeth in their post-treatment positions is the most challenging aspect of an orthodontic treatment.
CAUSES OF RELAPSE
Periodontal Factors: Remodeling gingival and periodontal fibers takes a long time, even after the treatment. Any disruption in retentive protocol during this phase of remodeling can easily lead to relapse.
Incomplete Orthodontic Treatment: However, the patient sometimes wants to discontinue treatment midway, after extraction, or during the final stage before accomplishing the treatment goal. In such a scenario, the Orthodontist unwillingly removes the appliance, and these cases would easily relapse.
Occlusal Factors: A very well-interdigitated dentition with even occlusal and proximal contacts and ideal overjet and overbite are less likely to relapse.
Habits: If the cause of treated malocclusion is habits and if it persists even after the treatment, malocclusion can lead to relapse.
Ageing and Growth: Remodelling of soft and hard tissues continues throughout life. Post-treatment skeletal growth changes, changes in alveolar bone during ageing, changes in inter-canine, etc., can also cause relapse.
Soft Tissue Factors: Relapse can occur post-treatment if soft tissue harmony is not maintained.
Type of the Malocclusion Treated: Malocclusions like midline diastema, rotation, expansion, etc., have more chances of relapse, though some malocclusions are self-retentive.
HOW TO PREVENT RELAPSE
There is not a single way that is quite effective in preventing relapse. However, various techniques can be combined to retain the outcome successfully.
1. Patient Education: Educate the patient about the reasons behind relapses and stress the value of adhering to the retentive protocols. Monitor the case through regular periodic check-ups after the treatment. Negligence on the part of the patient in following the post-treatment guidelines is the most important cause of relapse.
2. Fixed Lingual Retainers (FLR): It is the best way to help retain the result, and FLR should be bonded before debonding the fixed orthodontic appliance. It is very effective, has better aesthetics, no need for patient cooperation, and provides life-long retention of the anterior segment. However, the bonding of the retainer is very technique-sensitive and requires the best quality materials in sufficient quantity to bring the assured result. It can be bonded using direct or indirect methods on the palatal/lingual aspect of the upper and lower anterior teeth. It is mandatory to provide FLR for malocclusions with high risk to relapse.
The Wire Used for FLR
Blue Elgiloy or Stainless Steel Round / Rectangular Wires: It is easy to adapt and bond, but they will not allow physiological movement of teeth, so they are not preferred nowadays.
Multi-Stranded Wires: 0.0215-inch 5-stranded wires serve better results and are commonly used for FLR. The wire bonded should be passive; otherwise, it leads to undesirable tooth movement.
Resin Fiber Glass Band Retainer (e.g.: Ribbond): They are highly aesthetic, easily manipulated, and effective methods for retention. However, it is expensive compared to wires and does not allow physiological movement, so it is preferred in patients with periodontal problems for splinting purposes in addition to FLR post-treatment.
Bonded Retainers Made by CAD-CAM System: Recently, retainers are made by bending prefabricated wires by the handle of a machine. Some of them are as follows.
The Sure Smile Retainer (OraMetrix, Richardson, TX, USA): Copper – nickel- titanium wire is used for making retainers in this system.
Memotain Retainer (CA-Digital, Mettmann, Germany): Bonded retainers are produced by carving out of a block of wire. 0.014 X 0.014 inch nickel- titanium wire is used to make a Memotain retainer.
3. Removable Retainers: They have the advantage of being easier to maintain oral hygiene. Good patient compliance is needed with these types of retainers. A removable type of retainer is mandatory after all types of orthodontic treatment.
• Hawley's Retainer: The most commonly used retainer is the Hawley's retainer. Most of the other retainers having wire components are the modification of this type of retainer. It is straightforward to fabricate, cost-effective, and easily adjusted chairside; less armamentarium is required for its fabrication.
• Thermoplastic Retainers (Essix Retainers): They are highly aesthetic and easy to wear and remove, making them very convenient for the patient. As no acrylic part extends to the palate like Hawley’s, it will not interfere with speech also. It is also cost-effective and slightly more effective in maintaining stability, particularly in the lower arch. You can also print a 3D model of the completed case and fabricate multiple backup clear retainers for easy replacement of broken or lost retainers in the future.
CONCLUSION
Although changes in tooth position may also occur as a normal part of the growth and ageing process, variation in tooth position after orthodontic treatment is more prominent and very concerning to the patient. Therefore, even after orthodontic treatment, the dentist's work is incomplete. However, in addition to providing all the appliances required for retention, routine check-ups will definitely be necessary to ensure that the patient complies with retention therapy, thereby also ensuring the stability of treatment outcomes. Patients who refuse to adhere to the clinician's instructions need to be prepared to accept their relapse as well.